Final diagnosis


Thanatephorus cucumeris

The stem and crown of these young melon plants are dark brown, corky in appearance, and shallowly rotten. <i> <b> Thanatephorus cucumeris </b> </i> (<i> Rhizoctonia solani </i>)
Rhizoctonia2
Rhizoctonia1
This melon root system is heavily altered by <b> <i> Thanatephorus cucumeris </i> </b> (<i> Rhizoctonia solani </i>). There are many brown and rotten roots, the collar shows a somewhat corky reddish-brown sleeve.
The roots show a multitude of brownish lesions. In places, we can clearly distinguish mycelium and some brown mycelial cords of <i> <b> Thanatephorus cucumeris </b> </i> (<i> Rhizoctonia solani </i>)
We can see, on the part of this melon in contact with the ground, a large irregular lesion, more or less superficially tawny to brown, and presenting small bursts. <b> <i> Thanatephorus cucumeris </i> </b> (<i> Rhizoctonia solani </i>)
The lesion caused on this fruit by <i> <b> Thanatephorus cucumeris </b> </i> (<i> Rhizoctonia solani </i>) was also partially colonized by at least one secondary invader including the white mycelium is visible in places.
A discreet brown mycelium walks over this portion of the root. <i> <b> Thanatephorus cucumeris </b> </i> (<i> Rhizoctonia solani </i>)
Isolated mycelium and brown mycelial cords are visible on this melon root. <i> <b> Thanatephorus cucumeris </b> </i> (<i> Rhizoctonia solani </i>)
The mycelium of phytopathogenic fungi such as ascomycetes and basidiomycetes (here <i> Rhizoctonia solani </i>), is <b> partitioned </b>.
The mycelium of <b> <i> Thanatephorus cucumeris </i> </b> (<i> Rhizoctonia solani </i>) is characterized by its robust appearance, a width between 5 and 15 µm and a dark brown coloration. . There is also a slight constriction at the lateral ramifications, as well as the presence of partitions.
Basidia (12-18 x 8-11) are quite rarely formed on the mycelium, surmounted by 3 to 7 sterigmas. The basidiospores are asymmetrical and measure 7-11 x 4-7 µm. <i> <b> Thanatephorus cucumeris </b> </i> (<i> Rhizoctonia solani </i>)